How to know when you need a tune-up
The modern "tune-up" is much less intensive than the days when car engines required frequent adjustment for everything from spark plugs to ignition timing and fuel-air mixture.
Since the 1990s, vehicles are heavily monitored and controlled by computers and sensors, and to a great extent "tune" themselves until the dreaded "check engine" light comes on.
These vehicles, however, still require regular maintenance. The manufacturer's recommended intervals can be found in the owner's manual. Each make, model and year is unique, and maintenance requirements will depend on what you drive, how often, and under what conditions.
What's now advertised as a "tune-up" is designed to keep your engine running smoothly and efficiently. This usually consists of changing the spark plugs, inspecting and replacing air and fuel filters as required, and in some cases extras such as fuel-injection service.
A tune-up is one of the more major service intervals, whereas something like an oil change is done on a routine basis – two or three times a year depending of course on mileage.
As for a tune-up, which includes changing the spark plugs, different vehicles have different servicing requirements. Some have really long life plugs, and some are shorter life. With the Alto for example, the tune-up maintenance interval is 60,000 kms or less, whereas a lot of the premium vehicles can go up into the 100,000-km mark before a first major tune-up.
Maintenance items are often discovered on checks conducted during a good-quality oil change. When it comes time to replace the spark plugs, in many cases the air and fuel filter have already been looked after.
While t varies with driving conditions a fuel filter should be changed every 25,000-40,000 kms. On the average vehicle, you'll get between 15,000-20,000 kms from an air filter. But if you're driving a lot of rough and dusty roads, you're going to change it a lot more often.
There are things like timing belts on a lot of vehicles for example; it's not considered a tune-up item per se, but it is considered for replacement at around 100,000-120,000 kms.